In the steam cracking industry of natural gas or naphtha, fouling of tubular heat exchangers by cokes is a major issue. This growing carboneous layer has two major negative effects: 1) it increases pressure drop and 2) reduces heat transfer from the tube wall to the processed fluid. Using the open-source Computational Fluid Dynamics software OpenFOAM, this study numerically investigates wall shear stress, pressure drop and heat transfer performances of swirl decaying flow generated by different elliptical cross-section twisted tube. One of the objectives is to determine if minor modifications of tube geometry can generate swirling flow which could enhance wall shear stress at a reduce pressure drop penalty. For a Reynolds number ranging from 10, 000 to 100, 000, it is shown that the investigated geometries could enhance heat transfer by 90% at an increased pressure drop of 128% which yields a Performance Evaluation Criterion (PEC) of 1.44. The comparison between the performances of the different geometries is carried out using a newly defined PEC based on the bulk temperature, along with the usual PEC.
展开▼
